An elevator comprises an elevator car moving in a vertical direction upwards and downwards in an elevator shaft. The elevator car transports people and/or goods between the landings in a building. There are further guide rails being attached to the wall structure of the elevator shaft and extending vertically along the height of the elevator shaft. The car is guided in the lateral direction with gliding means gliding on the guide rails when the car moves up and down in the elevator shaft.
The cross section of the guide rails has normally the form of a letter T. The horizontal branch of the letter T is attached to support brackets being attached to the wall structure of the elevator shaft. The vertical branch of the letter T forms three gliding surfaces for the gliding means. There are thus two opposite side gliding surfaces and one front gliding surface in the guide rail. The gliding means comprises normally a frame part and a gliding part. The horizontal cross-section of the gliding part has the form of a letter U so that the inner surface of the gliding part sets against the three gliding surfaces of the guide rail. The horizontal cross section of the frame part has also a U-shaped section surrounding the gliding part on three sides. The frame part comprises further outwardly extending flanges at the bottom of the letter U for attaching the gliding means to the car sling. There are elasticity means between the gliding part and the frame part in order to isolate the gliding part from the frame part.
The guide rails are formed of rail elements of a certain length. The rail elements are connected in the installation phase end-on-end one after the other in the shaft. It is difficult and time consuming to align the guide rails so that each rail element is in a correct position when the rail element is attached′ to the support brackets. The alignment is done by forcing and/or moving the support bracket into a desired position with a hand tool after which the bolts are tightened in order to keep the guide rail in the desired position. The quality of the alignment will vary depending on the mechanic who is doing the alignment.